Electric pulse generating means



May 17, 1966 D. c. LOUDON 3,252,024

ELECTRIC PULSE GENERATING MEANS Filed Aug. 15, 1963 INVENTOR. DONALD C. LOUDON 3,252,024 ELECTRIC PULSE GENERATING MEANS Donald C. London, Sidney, N.Y., assignor to The Bendix Corporation, Sidney, N.Y., a corporation of Delaware Filed Aug. 13, 1963, Ser. No. 301,826 6 Claims. (Cl. 310-155) This invention relates to electrical apparatus and more particularly to devices for generating pulses of electrical energy.

One of the objects of the present invention is to provide novelly constructed means whereby timed pulses of electrical energy may be generated, such as pulses adapted for triggering electronic valves, electronic switching devices, relays, and the like.

Another object is to provide novel electrical apparatus of the above character which comprises a minimum number of parts that may be readily manufactured and assembled at relatively low cost.

Still another object is to provide novel electric pulse generating means which .is so constructed and operated that the pulses are generated by disturbance or distortion of the magnetic field in the vicinity of the pole of a stationary magnet.

A further object is to provide an electrical pulse generator which is admirably suited for use in an engine ignition system to provide accurate timing of the ignition sparks which varies in a desired manner with changes of engine speed or accurate timing that is unaffected by such changes of speed.

A still further object is to provide a novel and efiicient method of assembling and magnetizing apparatus of the above character to insure maximum output capability per unit of size and weight.

Another object is to provide a novelly constructed electromagnetic device of small size and convenient shape for generating relatively powerful electrical pulses.

The above and further objects and novel features of the present invention will more fully appear from the following detailed description when the same is read in connection with the accompanying drawing. it is to be expressly understood, however, that the drawing is for the purpose of illustration only and is not intended as a definition of the limits of the invention.

In the drawing, the single figure is an axial sectional view, with some parts shown in side elevation, illustrating one form of pulse generating apparatus contemplated by the invention.

The single embodiment of the invention illustrated in the drawing, by Way of example, is in the form of an electromagnetic device for generating electrical pulses adapted for triggering an electronic valve, such as in an engine ignition system, or for other comparable purposes, the same being capable of triggering said valve either at a fixed time during each pulsing cycle or at variable times during such cycle in response to variations in a reference speed. The apparatus as illustrated comprises .a rotor or triggering wheel 8 and a magnetic stator unit 9. The latter is shown as comprising a tubular casing 10 of aluminum or the like which may be a part of a larger housing that encloses other equipment, such as the parts of an ignition distributor.

An electrical connecting device 11 is mounted in the end of the casing and comprises two conductors or contacts 12, 14. Connector device 11 may be a part of a separable plug and socket type connector of any suitable known construction and the separable parts thereof may be held in assembled relation by a ring nut 16 which is illustrated as securing device 11 in the casing.

The pulse generating unit 9 of the invention cmprises electromagnetic means consisting of a novel assem- United States Patent 0 bly of parts which is combined in a novel manner with and supported by casing 10. As illustrated said assembly comprises a shell or housing 17 of non-magnetic material, such as brass, which telescopes with the cylindrical end portion of casing 10 and is secured thereto by staking at a number of circumferentially spaced places, as at 18, into a groove 19 in the outer wall of the casing. The other end of shell 17 is closed, except for a central opening 20, by a washer 21 which is also preferably made of non-magnetic material. Said washer may, if desired, be an integral part of shell 17.

Within shell 17, 21 and preferably seated against washer 21, is a coil 22 having the winding 23 thereof wound on a spool 24 of insulating material, such as nylon. The inner and outer turns of winding 23 are connected by leads 26, 27 to contacts 12 and 14. Mounted within spool 24 is .a longitudinally magnetized permanent magnet 28 which is preferably cylindrical and a combination pole piece .and coil core 29 of magnetic material, such as silicon iron which may be cadmium plated.

The pole piece 29 extends through washer 21 and is preferably provided with a radial shoulder 30 or the equivalent which engages washer 21 to limit movement of the pole piece and magnet to the right, as viewed in the drawing. The magnet and pole shoe 29 are held against movement toward the left by a spacer 31 of resilient insulating material, such as synthetic rubber or other nonmagnetic material. The spacer is interposed between connector 11 and magnet 28 under compression and greatly facilitates manufacture and assembly of the whole device since it takes up the tolerances permitted in the manufacture of the individual parts. For reasons to hereinafter appear pole piece or core 29 extends into coil 23 to approximately the axial mid point thereof.

In order to improve the output ability of the assembled unit 9, it is preferable to magnetize the magnet 28 in situ after assembly. the charging block of an external magnetizing machine but is preferably accomplished by energizing coil 23 in a condenser discharge circuit. To stabilize the magnet most useful point on the BH demagnetizatron curve for the material used and hence maximize the permanent magnetic charge induced into the magnet, a plate or disc 32 of steel or other magnetic material is interposed between the upper or left end of magnet 28 and spacer 31, as illustrated in the drawings, and the unit is temporarily placed in cup-shaped fixture or casing 38 of magnetic metal shown in dot-dash lines in the drawing. The lower or right end of casing 38 is shown with an opening for receiving pole piece 29 but the bottom of the the material of the high ampere turns and Will assume a strong permanent magnetic charge. When the temporary casing 38 is then removed, the lines are shown for periodically or intermittently disturbing or distorting the external magnetic flux field of magnet 28 Patented May 17, 1966 momentarily and sufficiently in relation to the turns of winding 23 to induce or generate momentary pulses of electrical energy in the winding and the circuit to which it is connected through terminals 12 and 14. In the form shown, said triggering wheel is made of a magnetic material, such as sheet steel, and comprises a hub portion 33 drivably connected to a rotatably shaft 34. A plurality of arms or fingers 35 extend radially from and are preferably integral with hub portion 33. Fingers 35 are twisted, as at 36, through 90 so that the operative end portions or vanes 37 thereof are thin in the direction of motion as they rotate close to and past the outer end of pole shoe 29. Each electric pulse thus generated in winding 23 when a vane 37 passes through the magnetic flux field in the vicinity of the end of pole shoe 29 has the advantageous characteristic that it changes almost instantly from a maximum of one polarity to a maximum of the opposite polarity. This reversal occurs as'the thin finger portion or vane 37 passes the plane containing the longitudinal axis of the pole shoe and magnet. The vanes 37 do not appreciably vary the flux intensity of the magnetic field but rather merely distort or disturb the field causing relative movement of the lines of flux and the turns'of winding 23. Upon each passage of a vane a single pulse is generated in the winding without any oscillations. Because of the extension of the core 29 into 'the coil, a greater distortion of disturbance of the magnetic flux occurs during each passage of a vane 37 and hence a more powerful pulse is obtained than if the winding surrounded only the magnet. For optimum output, core 29 should extend to at least near the middle of the winding.

There is thus provided a novel electrical pulse generating apparatus which is rugged, yet of simple and inexpensive construction and which is capable of generating single distinct pulses of electrical energy at selected predetermined intervals in relation to a moving part, said pulses being without oscillations and admirably suited for triggering electronic valves, such 1 as silicon controlled switches, transistors, and the like, for any purpose and more particularly for controlling the operation of condenser discharge typeignition systems for combustion engines and the like. The novel unit 9 hereby provided is symmetrical and hence may be conveniently mounted without the necessity of orientation relative to the wheel 8. Additionally, the novel device contemplated by the invention is not direction sensitive so that the trigger wheel may be rotated in either direction.

Although only a single embodiment of the invention has been illustrated and described in detail in the foregoing specification, it is to be expressly understood that the invention is not limited thereto. Various changes may be made, such as inthe design and arrangement of the parts illustrated as well as in the materials suggested for use, without departing from the spirit and scope of the invention as the same will now be understood by those skilled in the art.

What is claimed is:

1. In electrical pulse generating apparatus, an electromagnetic unit comprising a core including a permanent bar magnet made of magnetic material such as aluminum nickel alloy and a bar of magnetic material such as silicon iron alloy, said bars being in abutting end-to-end relation, a coil wound around said core and electrically insulated therefrom, said bars projecting from opposite ends of said coil and having the abutting ends thereof in the vicinity of the axial midpoint of the coil, and nonmagnetic means securing said core .and coil in assembled relation. I

2. Electrical pulse generating apparatus as defined in claim 1 comprising a disc of magnetic material spanning the projecting end of said magnet and extending radially therefrom over an adjacent end of the coil.

3. Electrical pulse generating apparatus including an electro-magnetic unit comprising non-magnetic casing means having a central opening in one end wall thereof, a core member of magnetic material having a reduced pole shoe portion extending outwardly through said opening and a radial shoulder engaging said end wall around the opening, an axially magnetized permanent magnet in end-to-end relation with said coremember, means including a resilient block interposed between said magnet and the other end wall of said casing means to position the magnet and core axially of the casing means, a nonmagnetic spool surrounding the adjacent ends of said magnet and core member for positioning the same radially of the casing means, and an electrically conductive coil wound on said spool, the junction of said magnet and core -member being intermediate the ends of the coil.

4. In electrical pulse generating apparatus, the combination comprising an assembly of parts including a spool for-med of non-magnetic material, an electrically conductive coil wound on said spool, an axially magnetized permanent magnet extending into and projecting from one end of said spool, a core member of magnetic material extending into and projecting from the other end of said spool, and non-magnetic means holding the parts of said assembly in assembled relation.

5. In electrical pulse generating apparatus, the combination comprising an assembly of parts including a spool formed of non-magnetic material, an electrically conductive coil Wound on said spool, a magnetic flux conducting core extending through said spool and coil, 'said core comprising an axially magnetized permanent magnet and a substantially unmagnetized core member of magnetic material in end-to-end relation with the mag net, the junction of said magnet and core member being in the vicinity of the axial midpoint of the coil. 6. Electrical pulse generating apparatus as defined in claim 5 comprising a disc of magnetic material engaging the projecting end of said magnet and extending radially over the adjacent end of said coil.

References Cited by the Examiner UNITED STATES PATENTS 2,662,996 12/1953 Mart-in 310l X 3,158,033 11/1964 Cohen 310l55 X ORIS L. RADER, Primary Examiner.

MILTON O. HIRSHFIELD, Examiner.

J. SWARTZ, Assistant Examiner. 

1. IN ELECTRICAL PULSE GENARATING APPARATUS, AN ELCTROMAGNETIC UNIT COMPRISING A CORE INCLUDING A PERMANENT BAR MAGNET MADE OF MAGNETIC MATERIAL SUCH AS ALUMINUM NICKET ALLOY AND A BAR OF MAGNETIC MATERIAL SUCH AS SILICON IRON ALLOY, SAID BARS BEING IN ABUTTING END-TO-END RELTION, A COIL WOUND AROUND SAID CORE AND ELECTRICALLY INSULATED THEREFROM, SAID BARS PROJECTING FROM OPPOSITE END OF SAID COILS AND HAVING THE ABUTTING ENDS THEREOF IN THE VICINITY OF THE AXIAL MIDPOINT OF THE COIL, AND NONMAGNETIC MEANS SECURING SAID CORE AND COIL IN ASSEMBLED RELATION. 